Homogeneous polarized light is used in a variety of different applications. For example, homogeneous polarized light is used in microscopy to improve the visibility of objects that are not easily seen with conventional microscopes. Conventional microscopes with crossed polarizers, phase contrast microscopes and Differential Interference Contrast (DIC) microscopes all use homogeneous polarized light. These microscopes produce images which transform round-trip optical path differences or local anisotropy in the sample, to intensity variations in the image. The components and operation of these microscopes are well known as set forth in, “The Principles of Scanning Confocal Microscopy” by T. H. Wilson which is herein incorporated by reference.
However, inhomogeneous polarized light has not been considered for use in many applications, such as imaging systems in general and microscopes in particular. Although optical beams or light having radial or azimuthal inhomogeneous polarization have been produced, there are problems with the resulting optical beams or light.
For example, lasers, such as the concentric-circle-grating surface-emitting (CCGSE) semiconductor laser, can be used to generate azimuthally polarized light. Unfortunately, it is not easy to control which of the many possible azimuthal modes light emitted by the CCGSE laser will have. As a result, the azimuthally polarized light is of little use.
Spiral wave plates and diffractive elements in interferometers have also been used to produce optical beams with both types of polarization. Unfortunately, both of these approaches have, to date, produced beams of unsatisfactory quality and have required expensive fabrication procedures.